1. Field of the Invention
This invention relates to a diamond sintered compact excellent in economy as well as cutting edge strength, in particular, a diamond sintered compact tool whose diamond sintered compact layer thickness is decreased.
2. Description of the Prior Art
At the present time, diamond sintered compacts have been produced for applying to industrial uses such as cutting tools, dies, bits, etc., and used as a dresser, drill bit, wire drawing die, etc. for cutting or working nonferrous metals, plastics, ceramics, etc. Among these tools, in particular, a diamond sintered compact tool used for a cutting tool is generally composed of a tool material comprising a diamond sintered compact layer having a thickness of about 1 mm to 1.5 mm and a WCxe2x80x94Co cemented carbide substrate bonded therewith during a step where diamond grains are sintered with each other, the tool material being cut in a predetermined shape to give a cutting edge of a tool and then brazed to a tool body.
The above described diamond sinterd compact tool has excellent properties for cutting of non-ferrous metals, etc. and has already widely been used. However, since the diamond sintered compact has a higher tool unit cost because of its higher production or working cost as compared with other tool materials, it is indispensable to lower the tool unit cost in order to spread more widely the diamond sintered compact tool. As a trial to lower the tool unit cost, it is considered to decrease the cost for raw materials or finishing a cutting edge by decreasing the thickness of the diamond sinterd compact layer. However, a diamond sintered compact tool having a diamond layer thickness of 0.8 mm to 1.5 mm has ordinarily been used in spite of that in practical uses of the diamond sintered compacts, there are often cases where a thickness of at most 0.5 mm is sufficient. This is Probably due to occurrence of a problem that when the diamond layer is thinner, the strength of the diamond sintered compact is decreased in spite of the material being a same diamond sintered compact and breakage resistance during working is inferior.
It is an object of the present invention to provide a material for a high strength diamond sintered compact tool, whereby the above described problems of the prior art can be solved.
It is another object of the present invention to provide a diamond sintered compact tool having an excellent cutting edge strength and high breakage resistance with a low production cost.
These objects can be attained by a diamond sintered compact cutting tool comprising a diamond sintered compact sintered at an ultra-high pressure and high temperature range such that diamond is present in stable manner and a WCxe2x80x94Co cemented carbide substrate directly bonded to the diamond sintered compact during a step of sintering and brazed to a tool body through the WCxe2x80x94Co cemented carbide substrate in which a ratio of the thickness of the WCxe2x80x94Co cemented carbide substrate to the thickness of the diamond sintered compact layer satisfies the relation of:
0.8xe2x89xa6WCxe2x80x94Co cemented carbide substrate/diamond sintered compact (Poly-Crystalline Diamond, PCD) layerxe2x89xa63.0
and the diamond sintered compact layer has a thickness of 0.05 mm to 0.45 mm, preferably 0.12 mm to 0.36 mm.